Process for the polycondensation of organosilicon compounds in the presence of tin catalyst

ABSTRACT

ORGANOSILICON COMPOUNDS CONTAINING A SI-OH GROUP ARE POLYCONDENSED USING CYCLIC ORGANOTHIO-TINS OF HIGH CATALYTIC ACTIVITY OF FORMULA   (R&#39;&#39;-)2-SN&lt;(-S-(CH2)N-COO-R-OOC-(CH2)N-S-SN(-R&#39;&#39;)2-S-(CH2)N-   COO-R-OOC-(CH2)N-S-)   IN WHICH THE SYMBOLS R, INDEPENDENTLY REPRESENT A DIVALENT HYDROCARBON RADICAL OR A DIVALENT RADICAL CONSISTING OF DIVALENT HYDROCARBON RADICALS BONDED BY -O-, -CO-, -COO- OR -CHOH- RADICALS, THE SYMBOLS R&#39;&#39;, INDEPENDENTLY REPRESENT MONOVALENT HYDROCARBON RADICALS AND N REPRESENTS A POSITIVE INTEGER.

nited "States Patent Office 3,819,673 Patented June 25, 1974 3,819,673PROCESS FOR THE POLYCONDENSATION F ORGANOSILICON COMPOUNDS IN TIE PRES-ENCE OF TIN CATALYST Ferenc Sagi, Bron, and Michel Roussos, Lyon,France, assignors to Rhone-Poulenc S.A., Paris, France No Drawing. FiledMar. 23, 1972, Ser. No. 237,514 Claims priority, applic7altitagsFrance,Mar. 24, 1971,

Int. Cl. C07f 7/02, 7/08, 7/18 US. Cl. 260-448.2 E 10 Claims ABSTRACT OFTHE DISCLOSURE Organosilicon compounds containing a SiOH group arepolycondensed using cyclic organothio-tins of high catalytic activity offormula in which the symbols R, independently represent a divalenthydrocarbon radical or a divalent radical consisting of divalenthydrocarbon radicals bonded by O-, CO-, COO or CHOH-- radicals, thesymbols R, independently represent monovalent hydrocarbon radicals and nrepresents a positive integer.

The present invention provides a process for the polycondensation oforganosilicon compounds in the presence of certain tin compounds.

The tin compounds used in the process of the invention are cyclicorganothiotins corresponding essentially to the following formula II andin which x represents an integer, the formula III compound apparentlybeing in equilibrium with the formula I compound. The presence of smallamounts of the formulae II and I I! compounds, e.g. up to about does notappear to modify the catalytic activity of the organothiotin compound ofthe formula I.

in the compounds of formulae I, H and III the symbol -R can, forexample, represent an alkylene radical such as those with 2 to 13 carbonatoms, an arylene radical, such as phenylene, biphenylene, xylylene oror one of the above-mentioned radicals substituted by one or more alkyl,aryl, cyclohexyl or alkoxy radicals; R can also represent apolyoxyalkylene radical, particularly a polyoxyethylene orpolyoxypropylene radical, or a "O-R"-- radical in which R represents analkylene or arylene radical, for example, one of those specificallymentioned above.

Specific examples of symbol R are those where the diol HO-ROH is1,2-ethanediol; 1,3-propanediol; 1,2-propanediol, 1,2-butanediol;1,3-butanediol, 1,4-butanediol; 2,3-butanediol; catechol, resorcinol,hydroquinone and their derivatives substituted on the benzene ring, asfor example, 3,5-dimethylcatechol, 2,5-dirnethylhydroquinone,2,2'-dihydroxy-diphenyl, 3,3'-dihydroxydiphenyl,4,4'-dihydroxy-diphenyl, phenylhydroquinone, 4-phenyl-pyrocatechol andtheir derivatives substituted on the benzene rings;3,3-dihydroxy-diphenylmethane; 4,4-dihydroxy-diphenylmethane and theirderivatives substituted on the benzene rings; hydrobenzoin,phenylethylene glycol, benzopinacol, diethylene glycol, triethyleneglycol, dipropylene glycol, o-xylene glycol m-xylene glycol, p-xyleneglycol, 2,2-dihydroxy-dipropyl ether, 3,3'-dihydroxy-dipropyl ether and4,4'-dihydroxy-dibutyl ether.

The symbol 'R' can represent an alkyl radical with 1 to 20 carbon atoms,an alkenyl radical with Z to 20 carbon atoms or an aryl or aralkylradical such as methyl, ethyl, butyl, n-octyl, iso-octyl, myricyl,phenyl, tolyl, vinyl, allyl, benzyl and xenyl radicals. in practicehowever, radicals with 4 carbon atoms to 12 carbon atoms are preferred.

The value of n is usually 1 to 18, and is preferably 1 to 4.

The silicon compounds which can be polycondensated in the presence ofthe derivatives of the formula I should contain at least an Si-OH group.They can contain other types of functional groups (Si-X) which reactwith water to give SiOH groups, or which react with the SiOH groups toform SiO-Si bonds with elimination of HX. Thus, a silicon compoundcontaining SiX groups will be mixed with the formula I catalyst. Byexposing the mixture to humidity, the hydrolysis of the SiX groups willproduce SiOH groups, the condensation of which will be accelerated bythe presence of the catalyst.

The symbols X can represent hydrogen, alkoxy, groups such as methoxy,ethoxy or --OCH Cl-I OCH;,, acyloxy groups such as acetoxy,propionylox'y or benzyloxy, and ketoxime groups such as O-N=C(CHaldoxime groups such as --O--N=OHCH carbamate groups such as 0(C2Hi)2N-C R "NO- groups where R" is a methyl, ethyl or phenyl radical;and halogen atoms such as Cl, Br and F as well as any hydrolysable groupattached to the silicon atom.

There are between 0.9 and 3 other substituent groups on each atom of thesilicon reactant. They can be hydrocarbon radicals, for example, alkylradicals such as methyl, ethyl and propyl radicals, alkenyl radicalssuch as vinyl, allyl or hexenyl radicals, cycloalkyl radicals such ascyclohexyl, cyclopentyl and methylcyclohexyl radicals, cycloalkenylradicals such as cyclohexenyl, aryl radicals such as phenyl, tolyl,xenyl and Xylylenenaphthyl radicals, and aralkyl radicals such as benzyland phenylethyl radicals.

They may also be halogenated hydrocarbon radicals such as chloromethyl,'y-chloropropyl, bromooctadecyl, chlorophenyl, fluorocyclohexyl,chlorobutenyl, a,a,a-trifiuorotolyl and 3,3,3-trifluoro-propyl radicals.They may also consist of hydrocarbon chains linked by O, COO, CO-- orCHOH- radicals, such as (CH -OOC-Me and -(CH COOEt; they can also behydrocardon radicals substituted by --CN, NH CONH or SH radicals such as(CH CN, CH CN and C H --CN.

The organosilicon compounds have diiferent structures combining speciesof the type RSiO R SiO and R SiO The atoms of silicon can also be linkedamong themselves by atoms or radicals other than oxygen, such asdivalent radicals, e.g. methylene, dimethylene, hexamethylene andphenylene or hydrocarbon ether radicals such as C H OC H or withsilazane links e.g.

Si-NH-Si or SiNSi;

or with SiSSi links.

Certain of the organothiotin compounds of the formula I, as well astheir method of preparation, have already been described in GermanPatent Specification No. 1,020,335. They can be obtained by the reactionof a 10,10- dithiodiester with a di(organo)-tin oxide, the w,w'-dithi0-ester being itself obtained by the diesterification of a glycol by aw-thioalkanoic acid.

Other organothiotin compounds of formula I are new compounds and thesenew compounds form a further aspect of the present invention. The newcompounds are those of formula I where each R is a C H radical, R is ap-xylylene radical or a radical and n=1.

The new compounds may be prepared by a method analogous to the knownmethod, that is by reacting a di-octyl tin oxide with the diesterobtained by reacting thioglycollic acid with 2,2'-dihydroxydipropylether or p-xylylene glycol.

The organothiotin compounds of formula I show a remarkable catalyticactivity, superior to that of the tin derivatives already used, arestorage stable and stable when used under exceptional conditions.

Their high activity allows them to be used in smaller amounts, incomparison to the tin catalysts previously used, to achieve anequivalent final result. If they are used in equivalent amounts to theamounts used hitherto, then a more rapid catalysis results or a lowercatalysis temperature can be used. Their stability allows their use asaqueous emulsions for catalysing the polycondensation of organosiliconcompounds in emulsion.

The catalysts used in the present invention can be used under the sameconditions as the tin catalysts used hitherto in the polycondensation,such as diorganotin dialkanoates. Thus the concentration of catalyst canvary between 0.01 and 3% expressed as the weight of tin relative to thesilicon derivatives used and the polycondensation temperature can be C.to 200 C.

Examples 1 and 2 illustrate the product of novel compounds of formula Iwhile the subsequent examples illustrate the polycondensation process ofthe invention.

EXAMPLE 1 368 g. (4 mols) of thioglycollic acid HS-CH COOH (as an 80%strength aqueous solution), 281 g. (2.1 mols) of 2,2'-dihydroxy-dipropylether and 200 g. of toluene are introduced into a flask equipped with astirrer.

The flask is heated to reflux the toluene for two hours during whichtime about 80% of the theoretical amount of water produced in thereaction is removed azeotropically. To complete the esterification, 3.2g. of para-toluenesulphonic acid are added, and after 3 hours ofreaction,

practically all the theoretical amount of water formed by theesterification reaction can be removed.

The toluene solution is cooled to about 20 C., washed three times with100 cmfi. of an aqueous solution containing 5% of NaHCO and then twicewith 100 cm. of pure water. The organic phase is then dried overanhydrous sodium sulphate and filtered.

636 g. of a solution containing 508 g. of the desired ester (theory 564g.) corresponding to the formula CH3 CH3Hs-crh-oo0-dH-CHr-0-0Hr-dH-0OC-CHz-S H are obtained.

483 g. of the solution obtained above, 520 g. of dinoctyl-tin oxide[OSI1(C8H17)2] and 400 g. of toluene are introduced into a flaskequipped with a stirrer.

The mixture is boiled for 10 hours during which time 17.5 g. of H 0 areremoved azeotropically. After cooling, the product is filtered to remove1.4 g. of residue which had not reacted. The filtrate is washed twicewith 250 cm. of an aqueous solution containing 5% of NaHCO and thentwice with 250 cm. of pure water. The toluene solution thus obtained isdried over anhydrous Na S0 It weighs 1,085 g. is straw yellow in colourand contains 670 g. of the desired organo-tin derivative correspondingprin- CH3 CH:

The tin content is 17.95% of the dry product, theoretical: 19.05%. Themolecular weight is 1,020i50 (osmometry), theoretical=1250.

EXAMPLE 2 1 mol (138 g.) of p-xylene glycol, 2.1 mols (193 g.) ofthioglycollic acid (in the form of an strength aqueous solution) and 400g. of toluene are introduced into a stirred flask.

Using the same procedure as described in Example 1, 487 g. of solutioncontaining 257 g. of the diester of the formula Sn Sn are obtained.

The tin content of the dry product is 17.9%, theoretical=18.9%. ResidualSH 1%.

EXAMPLE 3 This example shows the stability of the catalysts of formula Iand of their catalytic power.

An emulsion A of the catalyst is prepared by mixing an organic solutioncontaining:

43 g. of the toluene solution of Example 1 containing:

17.95% of Sn,

150.4 g. of zinc octoate containing 12% of zinc, diluted with 150.4 g.of toluene,

23.2 g. of toluene, and

23.2 g. of perchloroethylene,

with an aqueous solution consisting of: 11.3 g. of a polyvinyl alcoholknown by the name Rhodoviol 13/135 P and 100.0 g. of water.

The mixture is homogenised in a colloid mill and the resulting emulsionadjusted to a Sn content of 1% by the ad dition of 130 g. of water.

An emulsion B is prepared according to the same technique by adding thequantity of catalyst of Example 2 required to give 1% of Sn.

Emulsion C is prepared by replacing the catalysts of the invention by anequivalent amount of Sn in the form of di-n-octyl tin diacetate.

Emulsion D is prepared using the equivalent amount of .-Sn in the formof di-n-butyl tin diacetate.

A silicone emulsion, intended for the non-stick treatment of paper, isprepared by mixing 252 g. of a dimethylpolysiloxane in which about 50%of the chain ends are OH groups and 50% are OCH groups, and which has aviscosity at 25 C. of 2,000 cp., 9.2 g. of methylhydrogenopolysiloxane,the chain ends of which are (CH SiO and containing 36.5% of SiH, 34 g.of a dimethylpolysiloxane with terminal -OH groups, and of viscosity 30cp. at 25 C., 80 g. of a 50/50 by volume mixture of toluene andperchloroethylene and 180 g. of the aqueous solution of Rhodoviolprepared as above.

The silicone emulsion is produced in a colloid mill, and then adjustedto a silicone content of 40% by the addition of 168 g. of water.

25 parts by weight of the silicone emulsion, 5 parts of the catalystemulsion A, B, C or D, and the water necessary to bring the total volumeto 200 cm. are mixed together. The resulting catalysed emulsion isapplied to paper by means of a glass rod. After drying the treated paperat 120 C. for 2 minutes, the silicone is polycondensed. A determinationshows that approximately 0.7 g. of active silicone matter remains per m?of paper.

A similar treatment of paper is carried out with the catalysed dilutedemulsions mentioned above, but after they have first undergone a naturalaging of 6 hours.

The papers treated in this way are subjected to a selfadhesion test byapplying an adhesive tape, known under the name Sparadrap, to the paperand by measuring the force necessary (in g./cm.) to remove the tape bypulling at an angle of 180. The removed tape is then applied to a steelsheet and the force necessary to detach it from the steel sheet ismeasured. Finally the force necessary to detach an adhesive tape whichhas not undergone contact with the silicone paper and which has beendirectly applied to the steel sheet is measured.

This last measurement will be designated by the term standard adhesiom"the detachment from the paper will be designated: the non-stickcharacter; the detachment from the steel sheet after contact of the tapewith paper will be designated; the subsequent adhesion. The resultsobtained are given in Table I below. The quality of the siliconetreatment of the paper will be the higher the lower is the non-stickcharacter and the closer is the subsequent adhesion to the standardadhesion.

TABLE I Catalyst emulsion aged for 6 Fresh catalyst emulsion hours Non-Subse- N on- Subse- The good performance of the papers treated with theemulsion catalysed with the catalysts A and B can thus be seen.Catalysts C and D, give a weak subsequent adhesion; this demonstrates amigration of the silicone from the treated paper to the adhesive tape,and thus a loss of adhesion to the latter.

EXAMPLE 4 The same tests are repeated by treating the papers asdescribed in Example 3, but the curing of the silicone is carried outonly at C. for 30 seconds. The results of the tests are given in thefollowing Table II below.

TABLE II Catalyst emulsion aged for 6 Fresh catalyst emulsion hours Non-Subsc- Non- Subsestick quent stick quent Standcharadhe- Standcharadhe-Catalyst ard actor sion ard acter sion These curing conditions show thatthe reactivity of the catalyst emulsions A and B is still adequate forthem to provide the desired properties, whilst emulsions C and D have aless pronounced non-stick character and give too great a migration ofthe silicone of the paper to the adhesive.

EXAMPIJE 5 A solution is prepared of 28 parts of a dimethylsiloxanerubber, the chain ends of which are blocked by OH groups and theWilliams plasticity of which is 150, 2 parts of amethylhydrogenopolysiloxane, the chain ends of which are blocked by (OH'Si'O groups and the Si-H content of which is 47% by weight, and 70parts of toluene.

Solutions E, F and G to be used in treating papers, are prepared asfollows: To 34 g. of the above-mentioned solution are added 0.38 g. ofthe solution of Example 1, 0.10 g. of acetic acid and 166.0 g. of oil C(petroleum fraction boiling between 72 and 98 C.). The resultingsolution is designated solution B.

In the same way, a solution F in which the tin catalyst is replaced bythe solution of Example 2 is prepared. Finally, in the same Way, asolution G is prepared in which the tin catalyst is di-n-butyl-tindilaurate, containing an equivalent amount of Sn.

Using these solutions, the silicone is applied to the paper by means ofa glass rod. After drying the treated paper at 120 C. for 2 minutes, thesilicone is polycondensed. A determination shows that above 0.4 g. ofactive material remains per m2 of paper.

This paper is subjected to the same tests as those described in Example3 and the results are given in Table III below.

TABLE III N on-sti-k Subsequent Solution Standard character adhesion E 6163 F 172 8 165 G 168 19 150 EXAMPLE 6 The procedure described inExample is repeated but the paper is dried only at 80 C. for 30 seconds.

The results of the tests are given in Table IV.

TABLE IV N on-stick Subsequent Solution Standard character adhesion E158 9 150 F 172 13 167 G 170 36 148 This table shows that with thesolutions E and F, the catalysis is still very adequate, although withthe solution G, the non-stick character becomes mediocre and themigration of the insutficiently catalysed silicone becomes too great.

EXAMPLE 7 In this example, the catalysts are used for curing a nonsticksilicone resin. It is difiicult to estimate the non-stick character of asilicone coating on a solid support, because the choice of adhesivematerial must show a sufiicient grab to limit the number of measurementswithin a suitable time. It must nevertheless permit sufficientmeasurement to represent as well as possible the permanent use to whichthe silicone will be submitted.

The test described here consists of cooking omelettes, which have beensalted and peppered, on a metallic support, previously coated with acured silicone coating. The silicone composition used in the coating isthe following: 3.1% by weight of a methylphenylpolysiloxane resincontaining 4% by weight of OH groups, bonded to the silicon; 0.55 phenylgroup per silicon and 1.35 phenyl and methyl groups per silicon; 0.01%of the monoethyl ether of dipropylene glycol; 0.20% ofdimethylpolysiloxane fluid, the chain ends of which are blocked by OH-groups, proportion of OH:4.2%; 1.79% of methyltriacetoxysilane and94.90% of l,l,1-trichloroethane.

Various samples of this resin are catalysed with the tin salts shownbelow so that there is 0.27% by weight of catalyst relative to the resindescribed above. In this case, the less tin the active moleculecontains, the less of it calculated as metal is present.

Resin 1 contains the catalyst of Example 1,

' Resin 2 contains the catalyst of Example 2,

Resin 3 contains di-n-butyl-tin dilaurate, Resin 4 containsd-n-butyl-tin diacetate, Resin 5 contains di-n-octyl-tin diacetate, andResin 6 contains di-n-octyl-tin dilaurate.

Each catalysed composition is placed in a closed glass container. Eachis tested immediately after catalysis and after storage for 6 months.

The catalysed resins thus obtained are applied to aluminium egg pans, of12 cm. diameter. These pans are previously carefully degreased, thencoated with the catalysed resins. The solvent is evaporated in about 15minutes and the resin is finally cured by stoving at 150 C. for 30minutes.

The eggs are beaten, salted and peppered. No greasy matter whatsoever isused. The pan is heated on a Bunsen burner thus allowing a temperatureof 250 C. to be reached on the treated face. 10 cm. of beaten eggs aredeposited, left to cook for 1 minute and the resulting omelette isremoved with a wooden spatula. The pan is rapidly cooled by placing iton a cold metallic body. The treated face is then at about 80 C. after1.5 minutes. The pan is heated again to 250 C. and the operation isbegun again. After every omelettes the pan is allowed to cool to about20 C. and the cycle is repeated.

8 Table V below shows the number of omelettes that can be cooked andremoved from the pan without sticking to the surface.

With resins 1 and 2, the number of omelettes made is in excess of 80,the test having been stopped at this value. The other resins do notbegin even to approach this number. Thus with resin No. 3 for example,sticking begins at the 36th omelette and, if the test is continued alittle longer until the 42nd omelette, it becomes practically impossibleto separate the omelette from the pan.

It is also noteworthy that the efficacy is maintained at a high levelwith the resins stored for -6 months in the cases of No. 1 and No. 2, inaccordance with the invention; in cases 3, 4, 5 and 6 the efiicacy hasdiminished, compared to that of the freshly catalysed resin.

EXAMPLE 8 The same tests are repeated, this time catalysing the siliconeresin with a constant proportion of tin, the tin being supplied by thecatalysts already described in Example 7.

The concentration of tin is 1% by weight relative to the quantity ofactive silicone matter. It is then noted that the efi'icacy of theresins containing the catalysts of the invention always remains superiorto that of the resins containing the tin compounds used hitherto.

We claim:

1. A process for the condensation of a first organosilicon compoundhaving at least one hydroxy group directly bonded to silicon with asecond organosilicon compound having at least one reactive atom or groupdirectly bonded to silicon where the reactive atom or group is hydrogen,halogen, alkoxy, acyloxy, ketiminoxy, aldiminoxy, carbamato or aminoxywhere the condensation is carried out in the presence of a tin catalystessentially of the general formula:

Sn S

in which the symbols R, independently represent a divalent hydrocarbonradical or a divalent radical consisting of divalent hydrocarbonradicals bonded by -O, --CO-, -C00 or CHOH- radicals, the symbols R,independently represent monovalent hydrocarbon radicals and n representsa positive integer.

2. A process according to claim 1 wherein the second organosiliconcompound has at least one reactive hydrogen atom or acyloxy groupdirectly bonded to silicon.

3. A process according to claim 1 wherein the first organosiliconcompound is a dimethyl polysiloxane having terminal hydroxy groups or amethyl phenyl polysiloxane having terminal hydroxy groups and the secondorganosilicon compound is a methyl hydrogeno polysiloxane or methyltriacetoxy silane.

4. A process according to claim 1, wherein each R' represents an alkylor alkenyl radical containing up to 20 carbon atoms.

5. A process according to claim 1 wherein each R represents an alkyleneradical having 2-13 carbon atoms or an arylene radical containing 1 or 2aromatic rings or such an alkylene or arylene radical interrupted by oneor more --O- links.

6. A process according to claim 1 wherein n=1-18.

7. A process according to claim 1, wherein each R represents CgHn, Rrepresents a p-xylylene radical or a radical and each n=1.

8. A process according to claim 1 wherein each silicon atom in theorganosilicon compound which is condensed contains on average 0.9 to 3hydrocarbon or halogenated hydrocarbon radicals, hydrocarbon radicalsinterrupted by one or more -O-, COO-, CO, CHOH- radicals, or hydrocarbonradicals substituted by one or more CN-, NH CONH or SH groups.

9. A process according to claim 1, wherein the condensation is carriedout at 15-200 C.

10. A process according to claim 1, wherein the amount of catalyst usedis such that the weight of tin is 0.014% based on the weight oforganosilicon compound.

References Cited UNITED STATES PATENTS 10 DANIEL E. WYMAN, PrimaryExaminer P. F. SHAVER, Assistant Examiner US. Cl. X.R.

